1. Field of the Invention
The invention relates to a device for the automatic singling-out of sheets in the delivery of a sheet-fed rotary printing press. The device pertains to single-sheet delivery in the delivery of a sheet-fed rotary printing press with a chain delivery, in which gripper bars extending transversely to the sheet-transport direction are disposed on revolvingly driven transport chains and laterally spaced-apart sheet grippers are disposed on the gripper bars; the sheet grippers grip the sheets consecutively by their front edges; the delivery further comprises an adjustable control for delayed sheet release, consisting of revolvingly driven suction tapes supplied with suction air; the suction tapes grip the delayed-released sheet with suction and transport the sheet in the sheet-transport direction across a main sheet pile onto a sheet depository movably disposed on the printing-press frame.
2. Description of the Related Art
A device comprising such features is known from Japanese patent publication JP-Sho 61-112927. The device described therein permits the singling-out of individual printed sheets, particularly proofing sheets, and the delivery thereof at the rear end face of the delivery (in the sheet-transport direction). In order to single-out individual sheets, by means of an automatic control, the sheet grippers (holding a sheet at its front edge) of a gripper system of a chain delivery are opened in a delayed manner with respect to the instant of opening for sheet delivery on the main pile. The delayed opening is accomplished through the adjustment of the gripper-opening cam. At the same time, any existing stops for the sheet front edge on the main pile are lowered, for example through swiveling, with the result that the delayed-released sheet is gripped by revolvingly driven suction tape and is transported across the main pile onto the single-sheet depository. A similar device is also described in Japanese utility model publication Hei 5-27388.
It has become known heretofore from European patent publication EP-A 0 180 827 that, after the singling-out of an individual sheet, the actuators (operated for the singling-out of the individual sheet), the transport means, and the sheet stops of the main pile automatically reset to a zero position or are switched off. In an effort to deposit single sheets, there is provided in the system according to the above-mentioned JP-Sho 61-112927, a rake-like sheet depository, swivellable about a transverse shaft. The rake-like depository is disposed at the (in the sheet-transport direction) rear end face of the delivery, with the result that the sheet depository can be swivelled upwardly into an approximately vertical position so that it does not constitute an obstruction during production printing and does not unnecessarily impede the view into the printing press. The same publication also discloses a rake-like sheet depository, telescopically variable in the sheet-transport direction, for adaptation to different sheet sizes. Consequently, the singling-out of individual sheets necessitates extensive manual preparation before the system can operate automatically. The structurally very elaborate and complicated frame used as the sheet depository impedes the view of the operator also when it is in the raised position and it is rather easily exposed to damage.